Stabilization of carotene

ABSTRACT

WHERE R is a lower alkyl, such as methyl, or an alkoxy, such as an ethoxy group, are introduced into fodder products, such as grass flour, or oil solutions in order to preserve nutritive properties of such products or solutions.   Stabilizers for carotene, which retard its oxidation and protect it against destruction, and which are 3,5-di-carbonyl derivatives of 2,6-dimethyl-1,4-dihydropyridine, conforming to the general formula

United States Patent 1 Giller et al.

[ STABILIZATION 0F CAROTENE [76] Inventors: Solomon Aronovich Giller, ulitsa Pernavas 10, kv. 76; Gunar Yanovich Dubur, ulitsa Suvorova 1 17, kv. 12, both of Riga; Yan Rikhardovich Uldrikis, ulitsa Darza, 2, kv. 2, Elgava; Gunar Jamovich Tirzit, ulitsa Zhagatu, 22, kv. 33, Riga; Andrei Rohertovieh Valdman, ulitsa Lenina, 167, Riga; Ivan Markovich Zakharchenko, ulitsa P. Stuckhi, 9/1 I, kv. 4, Riga; Yazep Yanovich Spruz, ulitsa Lenina, 103, kv. 8, Rezekne; Vitaly Evgenievich Ronis, ulitsa Ermolovoi, 17, kv. 66, Moscow; Alexandr Andrejevich Makarov, P/o Lugovaya, 3, Moskovskaya Oblast, all of USSR.

[22] Filed: May 4, 1973 [2]] Appl. No.: 357,271

Related U.S. Application Data [62] Division of Ser. No. 269,391, July 6, 1972, abandoned, which is a division of Ser. No. 55,288, July 15. 1970, abandoned.

[30] Foreign Application Priority Data July 22, I969 U.S.S.R 1352174 [52] U.S. Cl 426/311; 252/403; 260/666 C; 426/182; 426/197; 426/210; 426/228; 426/268 [51] Int. 'Cl A231 1/26 [58] Field of Search 426/182, 194, 197, 210, 426/328, 228, 227, 311, 268; 260/666 C, 295 R, 584, 295.5 R, 297 R; 252/403, 405

[56] References Cited UNITED STATES PATENTS 2,015,359 3/1937 Salzberg et a1. 260/584 x 1 51 May 13,1975

2,198,214 4/1940 Musher 426/210 2,562,970 8/1951 Thompson 426/182 3,325,288 6/1967 Tung 426/182 x 3,438,781 4/1959 MacMillan et al 426/328 x OTHER PUBLICATIONS Chem. Abstracts, Vol. 51, (I9), 10,2l3g-l0,214f,

Chem. Abstracts, Vol. 53, (ll), 14,7131: to 14,7l3h, 6-1959.

Merck Index, Seventh Ed., pg. I434, 1960. Chem. Abstracts, Vol. 70, (7), 28,779e, 2-1969. Chem. Abstracts, Vol. 69, (15), 59,104q, 10-1968.

Primary ExaminerS. Leon Bashore Assistant ExaminerArthur L. Corbin Attorney, Agent, or Firml-Iolman & Stern [57] ABSTRACT Stabilizers for carotene, which retard its oxidation and protect it against destruction, and which are 3,5-dicarbonyl derivatives of 2,6-dimethyl-1,4- dihydropyridine, conforming to the general formula where R is a lower alkyl, such as methyl, or an alkoxy, such as an ethoxy group, are introduced into fodder products, such as grass flour, or oil solutions in order to preserve nutritive properties of such products or solutions.

2 Claims, No Drawings STABILIZATION ()F CAROTENE This is a divisional of application Ser. No. 269,391, filed July 6, 1972, now abandoned which in turn is a divisional of application Ser. No, 55,288, filed July 15, 1970, now abandoned.

The present invention relates to antioxidants, and more particularly to carotene stabilizers.

The present invention has a particular reference to the stabilization of carotene in oil solutions, in fodder, and in any other carotene-containing products.

The problem of carotene preservation in fodder products under long-term storage conditions is of great importance for the national economy.

Carotene is known to be an important component of fodder products, being essential for the normal development of farm animals. However, easy oxidizability of carotene results in considerable losses thereof under storage conditions of fodder products. Therefore stabilization of carotene in such preparations as oil solutions, and stabilization of carotene in grass flour or in products containing grass flour, prove to be of great importance for further development of animal husbandry.

For preserving carotene in grass flour and in those fodder which comprise grass flour, a number of stabilizers have been proposed, ethoxychin (3,2-dihydro-6- ethoxy-Z,2,ttrimethylquinolinel being most widely used for this purpose.

Ethoxychin was proposed (cf. E. M. Bickoff, A. L. Livingston, J. Guggolz, C. R. Thompson, 1. Agr. and Food Chem., I954, 2, 1229) as a most effective fodder antioxidant for stabilizing carotene of alfalfa.

A method of stabilizing carotene in grass flour with ethoxychin introduced thereinto in the form of a solution is disclosed in M. S. TZhedek, Authors Certificate g of the USSR No. 2l7270, i967.

Said substance exhibits a good stabilizing effect, but proves to be somewhat toxic when administered per os to white mice. Moreover, it should be noted, that the process of producing ethoxychin is rather complicated and requires the use of vacuum distillation techniques. The production of ethoxychin i also associated with fire and explosion hazards. Ethoxychin is inconvenient in storage and handling, being a thick fluid, easily oxi dizable, if stored in premises accessible to air.

The main object of the present invention is to provide a new stabilizer for preserving carotene in oil solutions, in fodder products, and in any other carotene containing products, which stabilizer would be less toxic, more convenient for storage and transportation, while being not inferior to ethoxychin as to the effec tivcness of carotene stabilization.

Said object is accomplished by using as carotene stabilizers 3,5dicarbonyl derivatives of 2,6-dimethyl-l ,4 dihydropyridines conforming to the general formula (I) where R is a lower alkyl or an alkoxy.

The following compounds may be cited as separate representatives of the said group of carotene stabiliz ers:

2,6-dimethyl-3,S-diacetyL l ,4dihydropyridine (ll),

2,6-dimethyl-3,S-dicarboethoxy-l ,4-dihydropyridine (III).

in stabilizing carotene in fodder products, the compound in the form ofa solution in ethanol. isopropanol, or a vegetable oil is used in such an amount that the content of the stabilizer in the resulting fodder prod ucts is 0.2 g per kg. When stabilizing carotene in an oil, the compound is used in an amount of 0.04 percent by weight of the oil solution of carotene.

The stabilizing and antioxidant properties of the abovementioned compounds become manifest, when they are studied for thermal autooxidation of an oil solution of carotene, The compounds conforming to the general formula (I) were mixed in various concentrations with an oil solution of carotene, and the mixture was subjected to thermal autooxidation at a tempera ture of C over a period of 72 hours. For comparing the results obtained in experiments with the use of the compounds conforming to the general formula (I), similar experiments were carried out with the use of ethoxychin.

For stabilizing carotene in grass flour, the latter, after drying, was mixed with a solution of compounds conforming to the general formula (I), then packaged in sacks and kept in storage premises. The content of carotene in the stabilized grass flour was periodically assayed. in a similar fashion grass flour was treated with ethoxychin, and the results were compared.

The results thus obtained have shown, that the herein-proposed compounds conforming to the general formula (1) exhibit stabilizing and antioxidant properties with respect to carotene, that is, said compounds inhibit autooxidation of carotene. Due to this, carotenecontaining products do not lose their nutritive properties during a period as long as 6 months, this being quite sufficient for winter storages.

Toxicological investigations of the above-said com pounds conforming to the general formula (I) have shown them to be non-toxic. Thus, when carrying out comparative studies of the acute toxicity of ethoxychin and 2,6-dimethyl-3 ,S-dicarboethoxy-l ,4- dihydropyridine, we have established the LD for ethoxychin, when administered per us to white mice, to be 2,900 mg/kg, whereas for 2,6-dimethyl-3,5- dicarboethoxy-l,4dihydropropyridine it exceeds 32,000 mg/kg. Repeated daily administration per es of 2,6-dimethyl-3,S-dicarboethoxyl ,tdihydropyridine to white rats in doses of 20 mg/kg during 6 months causes no toxic symptoms in the animals.

This is a sound proof of the fact that the hereinproposed compounds conforming to the general formula (l) are at least ll times less toxic than ethoxychin.

When bacon pigs are fed with products containing grass flour stabilized with 2,o-dimethyl-3,5- dicarboethoxy-l,4-dihydropyridinc, the accumulation of vitamin A in their liver increases from 7.7 to 15.6 meg/g, i.e., twice as much It should also be pointed out, that the compounds conforming to the general formula (I) are advantageous in being produced by a simple and effective method, residing in reacting acyl acetone or acetoacctic ester with urotropin in the presence of ammonium acetate in an organic solvent, such as isopropanol. The compounds conforming to the general formula (1), produced by this method, are obtained in the form of crystalline substances, with a yield equal to -80-85 percent 2,6-dimethyl-3 ,S-dicarboethoxyl ,4-dihydropyridine in a vegetable oil. After the mixing, the resulting stabilized grass flour was packaged in sacks and stored in a flat storage. The content of carotene in the samples was of the theoretical amount. 5 assayed once a month over a period of 6 months.

The compounds conforming to the general formula The variations observed in the content of carotene in (I) are stable when stored in conventional packages, the nonstabilized grass flour and in that stabilized with such as polyethylene sacks, and do not feature any ethoxychin and with 2,6dimeth vl-3,5-dicarboethoxycaustic or destructive properties. 1,4-dihydropyridine (lll) are illustrated in Table 2, for

Given hereinbelow are example, illustrating the ap- 10 the storage conditions as specified hereinabove.

Table 2 Storage Ambient Relative Carotene content in Increase in carotene time, tempera humidity, grass flour, mg/kg preservation with days ture,(7 the use of Noiistabilized Stabilized Stabilized Ethoxychin Coinpd. lll

with with ethoxychin conipd. lll

0 +8.0 86 169 153 154 30 -7.5 90 137 151 153 +1711 +l8.3 on *35 90 12 149 151 +21 1 +2115 90 18.1 62 in: 150 150 +2s.i +27 6 120 2.5 75 I06 140 145 +288 +315 150 6.7 04 97 131 134 +282 +286 l80 +103 75 83 115 +261 +288 plication of some of the compounds belonging to the A n be n from h data presented in Table Said group- It Should be pointed out, that the applicathe content of carotene in grass flour stabilized with 2,- tion of the compounds conforming to the general for y 7 F Y- A y py mula (I) as carotene stabilizers in fodder products is in 32 8 Storage ER}: 3 kf f 0f 6 gll i tf l a be no way limited to the examples that follow. w? er m non'sta U grass Under similar conditions, ethoxychin enhances the EXA LE 1 preservation ofcarotene by 26.1 percent, this being 2,7 fl percent less than in case of using 2,6-dimethyl-3,5-

Solutions of carotene in sun o wer oil were used, the dicarhoethoxyl AdihYdmPYridina concentration of carotene therein being 100 'y/ml. To w is Claimed is: 25 ml of Siad 501L150 there were addfid 001 g (If l. A method of stabilizing carotene contained in foddieinthyl-3,S-dicarboethoxy-l,4dihydropyridine (lll), der products, such as grass flour, comprising treating or 0.0l g of 2.6-dimethyl-3,S-diacetyl-l ,4- said fodder products with a 3,5-dicarbonyl derivative of dihydropyridine, or 0.01 g of ethoxychin. The resulting t ylihy py confmmlng 10 me solutions were placed into a temperature-controlled general formula: cabinet and kept there over a period of 72 hours at a H H temperature of 70C. The content of carotene in the 40 O 0 samples was determined colorimetrieally. I I

R C .C R The obtained results are presented in Table l. I

1'! C CH Table l 3 N 3 In oil solution .1 Compounds Quantity of Residual quantity of caro- 7 tested compoundioh Eq a s where R is selected from the group consisting of a lower alkyl and an alkoxy, said derivative being taken in the form of a solution in ethanol or in isopropanol or Blank stock '10 in a vegetable oil in such an amount that the content of Ethflxychifl 85 the stabilizer in the resulting fodder product is 0.2 g per Compound lll 0.04 86 g C d ll 0.04 82 ompoun 2. A method of stabilizing carotene in an oil solution I comprising introducing into said oil solution a 3,5-

The obtained data indicate, that 3,5-dicarbonyl dei y derivative. of y -L rivatives of 2,6-dimethy]-l,4-dihydropyridine feature dlhydmllyndmg Conformmg t0 the general formulal practically the same antioxidant properties with respect to thermal autooxidation of carotene, as ethoxychin.

The comparison of the carotene-stabilizing activity of 2,6-dirnethyl-3,S-dicarboethoxyl ,4-dihydropyridine (Ill) and 2.6-dimethyl-3,S diacetyl-1 ,4 dihydropyridine (II) shows, that the activity of 2,6- dimethyl-3 ,S-dicarboethoxy-l ,4-dihydropyridine is somewhat higher. 6S

EXAMPLE 2 Grass flour was used, prepared from cultivated fod' der grass by artificial drying thereof in hightemperature driersv 500 kg of dry grass flour were treated in a mixer with 5 lit. of a 2 percent solution of where R is selected from the group consisting of a lower alkyl and an alkoxy, said derivative being taken in an amount of 0.04 percent by weight of said oil solu tion of carotene. 

1. A METHOD OF STABILIZING CAROTENE CONTAINED IN FODDER PRODUCTS, SUCH AS GRASS FLOUR, COMPRISING TREATING SAID FODDER PRODUCTS WITH A 3,5-DICARBONYL DERIVATIVE OF 2,6-DIMETHYL-1,4DIHYDROPYRIDINE, CONFORMING TO THE GENERAL FORMULA:
 2. A method of stabilizing carotene in an oil solution comprising introducing into said oil solution a 3,5-dicarbonyl derivative of 2,6-dimethyl-1,4-dihydropyridine conforming to the general formula: 